Hollow fiber having inner wall into which comb polymer is introduced, hollow fiber impregnated with gel, and thin slice of fiber array

ABSTRACT

This invention provides hollow fibers impregnated with gel in which the gel firmly adheres to the inner walls of the hollow fibers due to the introduction of comb polymers on the inner walls of the hollow fibers. These hollow fibers impregnated with gel have no gaps at the interfaces between the inner walls thereof and the gel. Accordingly, analysis can be performed with high accuracy. Also, thin slices obtained by bundling these hollow fibers and then slicing this bundle have sufficient adhesion between the gel and the inner walls of the hollow fibers. This also prevents gel from becoming detached from the inner walls at the time of slicing or during operations such as hybridization.

TECHNICAL FIELD

The present invention relates to hollow fibers that are used incapillary electrophoresis or the like or thin slices of a hollow fiberarray that are used as, for example, members for DNA microarrays.

BACKGROUND ART

Recently, capillary gel electrophoresis has been employed in order toanalyze trace amounts of substances in organisms. The capillariesemployed in such a method utilize narrow tubes having inner diameters ofabout 100 μm. Thus, trace amounts of samples are sufficient for use, andsamples can be easily isolated. Members that are used for thecapillaries include plastics that are excellent in their transparency,such as those represented by glass or polymethyl methacrylate. Use ofcapillaries having a hollow portion impregnated with a gel such asacrylamide as a member for a DNA chip that can collectively analyzegenes has been attempted (WO 00/53736).

In order to analyze organism-associated substances such as DNA bycapillary gel electrophoresis or using DNA chips, gel must be firmlyretained inside a capillary.

When the volume of gel filling the hollow portion is reduced, however, agap is generated at the interface between the inner wall of a capillaryand the gel. At the time of analysis, a substance first flows into thegenerated gap, and this disadvantageously leads to lowered accuracy inanalysis. When a capillary is used as a member for a DNA chip, the DNAchip is constructed by, for example, bundling several capillaries andcross-sectioning the bundle. When gel does not sufficiently adhere tothe inner wall of the capillary, it disadvantageously becomes detachedfrom the capillary at the time of cross-sectioning. Further, gel becomesdetached from the capillary during analysis such as hybridization.

Introduction of a hydrophilic group on the inner wall of the capillaryhas been proposed as an example of a technique for enhancing adhesionbetween the inner wall of the capillary and a gel (U.S. Pat. No.5,015,350). This is, however, a technique for enhancing the adhesionbetween a gel and the capillary by coating the capillary forhydrophilization. Thus, the strength of the adhesion between a gel andthe inner wall is not sufficient, so that gel cannot be retained as thenumber of times that the capillary is used increases.

In the case of a glass capillary, a method for enhancing the ability ofa gel to adhere thereto by chemically modifying the inner wall thereofwith polyacrylamide has been developed (S. F. Y. Li et al., CapillaryElectrophoresis, 173, 1992). This is, however, a technique forprocessing a glass surface with a bifunctional coupling agent thatreacts with a silanol group on the glass surface. Accordingly, theeffect of this technique cannot be attained by non-glass capillaries.

There has been a proposed method in which the shaping of a polymercapillary is conducted simultaneously with gel impregnation of thehollow portion of the capillary, thereby obtaining a polymer capillaryhaving its hollow portion impregnated with a gel (JP Patent Publication(Kokai) No. 11-211694 A (1999)). With this technique, however, a gap isgenerated at the interface between the inner wall of the capillary and agel when the volume of the gel is reduced during the shaping of thecapillary.

Meanwhile, an attempt has been made in which hollow portions of poroushollow fibers are filled with water-insoluble polymers for the purposeof imparting functions such as hygroscopic properties and antistaticproperties (JP Patent Publication (Kokai) No. 8-188967 A (1996)). Thisis, however, a technique for imparting new functions to fibers, which isunrelated to the adhesiveness of the gel filling the hollow portion.

More specifically, no conventional means had existed in the past thatwould sufficiently overcome the problem of the gap generated at theinterface between the inner wall of the capillary and the gel when thevolume of the gel is reduced or the problem of the gel becoming detachedfrom the capillary when a DNA chip is constructed. Thus, it has beendifficult to utilize a capillary impregnated with a gel for capillarygel electrophoresis or as a member for a DNA chip.

DISCLOSURE OF THE INVENTION

An object of the present invention is to provide hollow fibers that canfirmly retain gel on the inner walls of their hollow portions. It isanother object of the present invention to provide hollow fibers havingtheir hollow portions impregnated with gel. It is a further object ofthe present invention to provide thin slices obtained by slicing abundle of hollow fibers having firmly immobilized gel in their hollowportions.

The present inventors have conducted concentrated studies in order toattain the above objects. As a result, they have found that introductionof comb polymers on the inner walls of hollow fibers resulted inenhanced adhesion between the inner walls of hollow fibers and the gelfilling the hollow portions. This can prevent, for example, the gel frombecoming detached from the inner walls of hollow fibers when the volumeof the gel is reduced, or when the DNA chip is constructed. This has ledto the completion of the present invention.

More specifically, the present invention is as described below.

1. Hollow fibers having comb polymers introduced on their inner walls.

Examples of comb polymers include those having polymerizable functionalgroups or hydrophilic functional groups. An example of the backbone ofthe comb polymer is polymethyl methacrylate.

2. Hollow fibers having their hollow portions impregnated with gel.

An example of a gel is one mainly composed of an acrylamide monomer.Such gel retains an organism-associated substance according to need.

3. A hollow fiber array prepared by bundling several hollow fibersimpregnated with gel.

4. Thin slices of the hollow fiber array prepared by cross-sectioningthe array according to 3.

The hollow fibers used in the present invention are organic fibers.Examples thereof include: polyamide fibers such as Nylon 6, Nylon 66,and aromatic polyamide fibers; polyester fibers such as polyethyleneterephthalate, polybutylene terephthalate, polylactic acid, polyglycolicacid, and polycarbonate fibers; acrylic fibers such as polyacrylonitrilefibers; polyolefin fibers such as polyethylene and polypropylene fibers;polymethacrylate fibers such as polymethylmethacrylate fibers; polyvinylalcohol fibers; polyvinylidene chloride fibers; polyvinyl chloridefibers; polyurethane fibers; phenolic fibers; fluorine fibers comprisingpolyvinylidene fluoride or polytetrafluoroethylene; and polyalkyleneparaoxybenzoate fibers.

Analysis by capillary electrophoresis is conducted by radiating lightfor detection from the outer wall side of the capillary. Thus, hollowfibers are preferably optically transparent, and examples of preferablematerials for hollow fibers are methacrylic resins exemplified bypolymethyl methacrylate (PMMA), polystyrene, or polycarbonate that haveexcellent transparency.

Hollow fibers may be porous or non-porous. The outer diameters of hollowfibers are 2 mm or smaller, and preferably 1 mm or smaller. The innerdiameters thereof are preferably 0.02 mm or larger.

In the present invention, the comb polymers that are introduced on theinner walls of the hollow fibers are composed of backbones (main chains)and side chains (branches), and examples thereof are shown in (a) or (b)below. These comb polymers allow the gel filling the hollow portions tobe firmly retained on the inner walls of hollow fibers.

(a) Comb Polymers Having Polymerizable Functional Groups on their Mainor Side Chains

Examples of polymerizable functional groups include vinyl, acrylate,methacrylate, and cyclic unsaturated functional groups such ascyclohexene groups. These polymerizable functional groups are preferablyintroduced at terminuses of main or side chains of comb polymers.

Polymer components that are used as main chains of comb polymerspreferably have affinity to a material used for hollow fibers. When amaterial used for hollow fibers is polymethyl methacrylate (PMMA),monomer components that are used as main chains of comb polymers arepreferably, for example, methyl methacrylate, methyl acrylate,2-hydroxyethyl methacrylate, acrylic acid, methacrylic acid, glycidylmethacrylate, 2,3-dihydroxypropyl methacrylate, glycerol methacrylate,2-hydroxyethyl acrylate, or 2-hydroxypropyl acrylate. Two or more kindsof these monomers can be copolymerized.

(b) Comb Polymers Having Affinity to a Gel Filling the Hollow Portions

As with the case of (a) above, polymer components that are hydrophilicwith materials used for hollow fibers should be selected as polymercomponents for main chains. Preferably, polymer components of sidechains have affinity sufficiently to the network structure of the gelfilling the hollow portion of the hollow fibers and are capable ofbecoming entangled with the network structure of a polymeric gel.

For example, if the gel filling the hollow portion is hydrophilic, aside chain polymer preferably has a hydrophilic functional group.Examples of a hydrophilic functional group include a polymer comprisinghydroxyethyl methacrylate, ethylene glycol, propylene glycol, vinylalcohol, acrylic acid, or acrylamide as a constitutional unit or acopolymer of two or more thereof. In addition thereto, a polymercomprising a hydrophilic functional group such as a hydroxyl, amino, orsulfonic acid group introduced at its terminus can be selected as a sidechain.

The molecular weight of the polymer that is introduced on the side chainis preferably between 20 and 300,000, and more preferably between 1,000and 10,000.

Comb polymers can be introduced on the inner wall of the hollow fiber byimmersing one end of the hollow fiber in a solution of comb polymers andsuctioning the solution from the other end. In such a case, the solutionof comb polymers introduced by suction is preferably discharged in orderto avoid blockage in the hollow portion or embrittlement of hollowfibers caused by dissolution of inner walls of hollow fibers. After thepolymer solution is discharged, a solvent that dissolves the combpolymers is allowed to evaporate by air-drying, and the comb polymersare then allowed to adhere to the inner walls of hollow fibers.

The concentration of the comb polymers are preferably 50% by mass orlower, and more preferably 1% to 10% by mass.

In order to allow the comb polymers described in (a) and (b) above touniformly adhere to the inner walls of hollow fibers, a solvent thatdissolves the comb polymers is preferably a good solvent for the combpolymers and a poor solvent for materials used for hollow fibers.Examples of preferable solvents include alcohols such as methanol,ethanol, and propanol, acetone, methyl ethyl ketone, acetonitrile,dioxane, dimethylformamide, dimethylacetamide, dimethylsulfoxide,toluene, and ethyl acetate. These solvents can be used solely or incombinations of two or more. When several solvents are used incombination, the solvents to be combined are preferably miscible witheach other, and solvents to be mixed are preferably solely good solventsfor the comb polymers.

In the present invention, the kinds of gel used to fill the hollowportions are not particularly limited. Examples of a gel that can beused include a gel prepared by allowing a cross-linked polymer to swellwith the aid of water, wherein the cross-linked polymer is prepared bycopolymerizing at least one monomer selected from among acrylamide,N,N-dimethylacrylamide, N-isopropylacrylamide,N-acryloylaminoethoxyethanol, N-acryloylaminopropanol,N-methylolacrylamide, N-vinylpyrrolidone, hydroxyethyl methacrylate,(meth)acrylic acid, allyl dextran, and the like with a polyfunctionalmonomer such as methylene bis(meth)acrylamide, or polyethylene glycoldi(meth)acrylate.

Examples of polymerization initiators that can be used include azo,peroxide, or redox initiators that can be dissolved in the solvent to beused. Examples thereof include 2,2′-azobisisobutyronitrile,2,2′-azobis(2-methyl butyronitrile)isobutyronitrile, benzoyl peroxide,and benzoyl peroxide/dimethylaniline.

Examples of other gels include gels such as agarose, alginic acid,dextran, polyvinyl alcohol, or polyethylene glycol and gels prepared bycross-linking these gels.

When the hollow fibers of the present invention are used for nucleicacid analysis, the gel used to fill the hollow portion is preferably anacrylamide gel. The concentration level of an acrylamide monomer ispreferably 2% to 20% by mass.

A gel is commonly used to fill the hollow portion of the hollow fiberthrough suction in vacuo, although the technique used therefor is notlimited thereto.

When the comb polymer as described in (a) above is used, a polymerizablefunctional group thereof is chemically bound to a gel component, therebyallowing the gel used to fill the hollow fibers to be firmly retained onthe inner walls of the hollow fibers. More specifically, a monomercomponent, which is a starting material for a gel component, fills thehollow fiber comprising the comb polymer described in (a) introduced onits inner wall, and a polymerizable functional group of the comb polymerdescribed in (a) is allowed to react with the monomer component whenpolymerizing monomer components.

When the comb polymer described in (b) above is used, a gel filling thehollow fiber can be firmly retained on its inner wall upon theentanglement of the network structure of the gel filling the hollowfiber and the side chain of the comb polymer (b).

In the present invention, examples of organism-associated substancesinclude those selected from the group consisting of the followingsubstances 1 to 3:

1. a nucleic acid, amino acid, sugar, or lipid;

2. a polymer comprising at least one of substance 1. above; and

3. a substance interacting with substance 1 or 2.

When a nucleic acid is used as an organism-associated substance, forexample, DNA can be prepared from a living cell by the method of Blin etal. (Nucleic Acids Res. 3. 2303, 1976), and RNA can be extractedtherefrom by the method of Favaloro et al. (Methods. Enzymol. 65, 718,1980). Also, chain or cyclic plasmid DNA or chromosome DNA can be used.A DNA fragment that has been cleaved with a restriction enzyme orchemically, DNA that has been synthesized with the aid of an enzyme orthe like in vitro, or DNA that has been synthesized chemically can beused as such DNA.

Organism-associated substances can be retained by the gel by physicallyembedding them in the gel or directly binding them to gel constituents.Alternatively, organism-associated substances may be first allowed tobind to carriers such as polymers or inorganic particles by covalent ornon-covalent bonds, thereby immobilizing the carriers in the gel.

An embodiment of a direct bond to a gel constituent is carried out byintroducing a vinyl group to a nucleic acid terminus and then allowingthe resultant to copolymerize with a gel constituent, such as acrylamide(WO 98/39351). Also, agarose is converted to imide carbonate by thecyanogen bromide method, and the resultant is bound to an amino group ofa nucleic acid having an aminated terminus, thereby gelating theagarose. Alternatively, a biotinized nucleic acid can be allowed toreact with avidinized agarose beads (for example, avidinized agarose,manufactured by Sigma), thereby obtaining agarose beads having nucleicacids immobilized thereon. The agarose beads having nucleic acidsimmobilized thereon can be immobilized in acrylamide gel or the like.

Several hollow fibers comprising the thus prepared gel comprising anorganism-associated substance retained thereby filling their hollowportions are bundled, and the bundle of fibers is cross-sectioned. Thus,thin slices of the hollow fiber array can be prepared.

Examples of methods for bundling several hollow fibers include: (a) amethod in which several hollow fibers are arranged in parallel andimmobilized on a sheet such as an adhesive sheet, and the sheet is woundin a spiral configuration, thereby forming a bundle; and (b) a method inwhich two porous plates with several openings are stacked, a hollowfiber is allowed to pass through each opening of these porous plates,and the interval between two porous plates is widened, thereby forming abundle.

In the method as described in (b) above, a tension should be imparted toeach fiber in order to maintain the regularity of the sequence after thefibers have been allowed to pass through the porous plates. Accordingly,fibers are preferably highly elastic, and examples thereof includematerials comprising methacrylic resins such as aromatic polyamide ormethyl methacrylate.

A bundle of hollow fibers is immobilized by causing resins or the liketo flow into the gap between two fibers. The immobilized bundle offibers is cross-sectioned using a microtome or the like. Thus, thinslices can be obtained. The thin slices preferably have thicknesses of 1mm or smaller.

The thin slices are employed for the collective analysis of severalgenes. Thus, the number of hollow fibers in one thin slice is preferablylarge. Preferably, 100 or more fibers are present per cm² thereon. Theouter diameters of the hollow fibers used are preferably small. They arepreferably 0.5 mm or smaller, and further preferably 0.3 mm or smaller.The inner diameters are preferably 0.02 mm or larger.

Organism-associated substances that are retained in hollow fibers inthin slices may differ depending on the type of hollow fiber.Alternatively, a group of several hollow fibers comprising the sameorganism-associated substances being retained therein may be placed inthin slices.

The thus prepared thin slices of hollow fiber arrays retainingorganism-associated substances are used as, for example, a tool forcollective analysis of genes.

This description includes part or all of the contents as disclosed inthe description of Japanese Patent Application No. 2001-232751, which isa priority document of the present application.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 schematically shows an apparatus for introducing a solution ofcomb polymers on the inner walls of hollow fibers, wherein referencenumeral 11 indicates a bundle of fibers, reference numeral 12 indicatesa vessel filled with a solution of comb polymers, reference numeral 13indicates a trap tube, and reference numeral 14 indicates a vacuum pump.

BEST MODES FOR CARRYING OUT THE INVENTION

The present invention is described in greater detail with reference tothe following examples.

Example 1 (1) Production of Comb Polymers Having PolymerizableFunctional Groups on their Side Chains

Methyl methacrylate (MMA, 100 parts), glycidyl methacrylate (GMA, 100parts), and azobisisobutyronitrile (AIBN, 0.5 parts) were added dropwiseto methyl ethyl ketone (MEK, 50 parts) at 80° C. in the nitrogen gasstream (50 cc/min) for 3 hours.

Thereafter, AIBN (0.1 parts) and MEK (70 parts) were added, theresultant was allowed to stand for 1 hour, AIBN (0.1 parts) and MEK (10parts) were added, the resultant was allowed to stand for 3 hours, andMEK (50 parts) was further added. Thereafter, methylhydroquinone (MEHQ,0.5 parts), triphenylphosphine (2.5 parts), and acrylic acid (99 mole %of GMA) were added. During these procedures, reaction was allowed toproceed for 30 hours while air was blown thereinto (100 cc/min), andcomb polymers (A) having vinyl groups added to their side chainterminuses were obtained. These copolymers had 25 mole % of vinyl groupsintroduced therein.

(2) Production of Hollow Fibers Comprising Comb Polymers IntroducedTherein

50 hollow fibers of polymethyl methacrylate (outer diameter: 300 μm,inner diameter: 200 μm, length: 60 cm, manufactured by Mitsubishi RayonCo., Ltd.) were bundled, and comb polymers (A) were introduced in theirhollow portions using the apparatus shown in FIG. 1. In FIG. 1, one endof fiber bundle 11 was connected to trap tube 13. Another end was placedin vessel 12 filled with polymer solution 1. Vacuum pump 14 wasactivated to introduce the polymer solution 1 in the hollow portions bysuction.

A part of the solution introduced by suction into the hollow portionswas transferred to the trap tube, and the solvent remaining on the innerwalls of the hollow portions was allowed evaporate by air drying. Thus,hollow fibers, the comb polymers (A) having been introduced on the innerwalls of their hollow portions, were obtained.

[Polymer solution 1] Comb polymer (A)  5% by mass 1,4-dioxane 95% bymass

(3) Production of a Hollow Fiber Array

Two porous plates (thickness: 0.1 mm) each comprising 49 pores in totalarranged in 7 rows in both lengthwise and breadthwise directions, havingpore diameters of 0.32 mm, and having the center-to-center distancesbetween neighboring pores of 0.42 mm were stacked. 49 hollow fibers ofpolymethyl methacrylate prepared in (2) above were allowed to passthrough each pore of these two porous plates. The interval between thetwo porous plates was 50 mm, and both ends were immobilized whilethreads were being stretched therebetween.

Subsequently, a starting material for resin was made to flow into thevicinity of the hollow fiber array and then allowed to harden.Polyurethane resin adhesives (Nippolan 4276, Coronate 4403, manufacturedby Nihon Polyurethane Industry Co., Ltd.) were used. After the resin hadhardened, the porous plates were removed. Thus, a resin block containinghollow fibers was obtained.

(4) Production of Oligonucleotide Having a Methacrylate Group

An oligonucleotide was synthesized using an automatic DNA/RNAsynthesizer (model 1394, manufactured by Applied BioSystems (formerly PEBiosystems)). In the final step of synthesis, the reaction was allowedto proceed using Aminolink II (manufactured by Applied BioSystems) tosynthesize an oligonucleotide having aminated terminuses.

The resulting GCAT with aminated terminuses (50 μl, 500 nmol/ml),glycidyl methacrylate (5 μl), and dimethylformamide (DMF, 5 μl) weremixed, the mixture was allowed to react at 70° C. for 2 hours, and 190μl of water was added thereto. Thus, GCAT having 100 nmol/ml ofmethacrylate groups (MA-GCAT) was obtained.

(5) Impregnation of Hollow Portions with Gel

Subsequently, a starting solution for a gel comprising the monomer andthe initiator with the following mass ratios was prepared.

Acrylamide   9 parts by mass N,N-methylenebisacrylamide   1 part by mass2,2′-azobis(2-methylpropionamidine) 0.1 part by mass dihydrochioride(V-50) Water  90 parts by mass

MA-GCAT prepared in (4) was added to the above solution in such a mannerthat the solution would comprise MA-GCAT at 0.5 nmol/l.

The hollow portions of hollow fibers in the resin block obtained in (3)were filled with this mixed solution, the block was transferred into ahermetically sealed glass vessel with its inside being saturated withmoisture, and the content of the vessel was allowed to stand at 70° C.for 3 hours for polymerization. Thus, a gel was generated, and a blockof a hollow fiber array having its hollow portion impregnated with gelwas obtained.

(6) Production of Thin Slices of a Hollow Fiber Array

This block of hollow fiber array was sliced to a thickness of 500 μm ina direction vertical to the direction of fibers to obtain thin slices.Gel did not become detached from the inner walls at the time of slicing.Thus, it was confirmed that the adhesion at the interface between theinner walls of the hollow fibers and the gel was sufficiently strong.The conditions of the gel in the hollow portions were observed using astereoscopic microscope. As a result, all the 49 hollow fibers wereimpregnated with acrylamide gel without any spaces.

Example 2

Thin slices of a hollow fiber array were prepared in the same manner asin Example 1, except that polymer solution 2 was used instead of polymersolution 1.

[Polymer solution 2] PMMA monoacrylate  5 parts by mass (molecularweight: 6,000) Toluene 95 parts by mass

Gel did not become detached from the inner walls at the time of slicing.Thus, it was confirmed that the adhesion at the interface between theinner walls of the hollow fibers and the gel was sufficiently strong.The conditions of the gel in the hollow portions were observed using astereoscopic microscope. As a result, all the 49 hollow fibers wereimpregnated with acrylamide gel without any spaces.

Example 3

Thin slices of a hollow fiber array were prepared in the same manner asin Example 1, except that hollow fibers of polycarbonate (outerdiameter: 250 μm, inner diameter: 130 μm, length: 60 cm, MitsubishiRayon Co., Ltd.) were used instead of hollow fibers of polymethylmethacrylate, and polymer solution 3 was used instead of polymersolution 1.

[Polymer solution 3] Comb polymer (A)  5 parts by mass1,4-dioxane/acetonitrile (12%/88%) 95 parts by mass

Gel did not become detached from the inner walls at the time of slicing.Thus, it was confirmed that the adhesion at the interface between theinner walls of the hollow fibers and the gel was sufficiently strong.The conditions of the gel in the hollow portions were observed using astereoscopic microscope. As a result, all the 49 hollow fibers wereimpregnated with acrylamide gel without any spaces.

Example 4 (1) Production of Comb Polymers Having Affinity to a GelFilling Hollow Portions-1

The comb polymer (A) obtained in Example 1 (1 part) and2,2′-azobis(2-methylpropionamidine) dihydrochloride (V-50, 0.1 parts) asan initiator were placed in a polymerization tube, they were dissolvedin 100 parts of hydroxyethyl methacrylate (HEMA), the inside of the tubewas deaerated, and the tube was then sealed to conduct polymerization at60° C. After the completion of the polymerization, the sealed tube wasopened and the content thereof was poured into ethanol. Thus, aprecipitate of the comb polymer (B) having polyHEMA added to its sidechain was obtained. A homopolymer of HEMA as a by-product wassupplemented in an ethanol phase.

(2) From Introduction of Comb Polymers to Production of Thin Slices ofHollow Fiber Array

Thin slices of a hollow fiber array were prepared in the same manner asin Example 1, except that polymer solution 4 was used instead of polymersolution 1.

[Polymer solution 4] Comb polymer (B)  5 parts by mass 1,4-dioxane 95parts by mass

Gel did not become detached from the inner walls at the time of slicing.Thus, it was confirmed that the adhesion at the interface between theinner walls of the hollow fibers and the gel was sufficiently strong.The conditions of the gel in the hollow portions were observed using astereoscopic microscope. As a result, all the 49 hollow fibers wereimpregnated with acrylamide gel without any spaces.

Example 5

Thin slices of a hollow fiber array were prepared in the same manner asin Example 3, except that polymer solution 5 was used instead of polymersolution 3.

[Polymer solution 5] Comb polymer (B)  5 parts by mass1,4-dioxane/acetonitrile (12%/88%) 95 parts by mass

Gel did not become detached from the inner walls at the time of slicing.Thus, it was confirmed that the adhesion at the interface between theinner walls of the hollow fibers and the gel was sufficiently strong.The conditions of the gel in the hollow portions were observed using astereoscopic microscope. As a result, all the 49 hollow fibers wereimpregnated with acrylamide gel without any spaces.

Example 6 (1) Production of Comb Polymers Having Affinity to a GelFilling Hollow Portions-2

The comb polymer (A) obtained in Example 1 (1 part) and V-50 (0.1 parts)as an initiator were placed in a polymerization tube, they weredissolved in 100 parts of polyethylene glycol monoacrylate (manufacturedby Aldrich), and the tube was then sealed to conduct polymerization at60° C. After the completion of the polymerization, the solution waspoured into water. Thus, the comb polymer (C) having polyethylene glycoladded to its side chain was obtained. A homopolymer of polyethyleneglycol monoacrylate as a by-product was separated in an aqueous phase.

(2) From Introduction of Comb Polymers to Production of Thin Slices ofHollow Fiber Array

Thin slices of a hollow fiber array were prepared in the same manner asin Example 1, except that polymer solution 6 was used instead of polymersolution 1.

[Polymer solution 6] Comb polymer (C)  5 parts by mass 1,4-dioxane 95parts by mass

Gel did not become detached from the inner walls at the time of slicing.Thus, it was confirmed that the adhesion at the interface between theinner walls of the hollow fibers and the gel was sufficiently strong.The conditions of the gel in the hollow portions were observed using astereoscopic microscope. As a result, all the 49 hollow fibers wereimpregnated with acrylamide gel without any spaces.

Example 7 (1) Production of Comb Polymers Having Affinity to a GelFilling Hollow Portions-3

The comb polymer (A) obtained in Example 1 (1 part) and acrylamide (100parts) were dissolved in 100 parts of ethanol, and an initiator solution(an aqueous solution of 10% ammonium persulfate, 0.1 parts) was addedthereto to conduct polymerization at 60° C. After the completion of thepolymerization, the solution was poured into water. Thus, the combpolymer (D) having polyacrylamide added to its side chain was obtained.Polyacrylamide as a by-product was separated in an aqueous phase.

(2) From Introduction of Comb Polymers to Production of Thin Slices ofHollow Fiber Array

Thin slices of a hollow fiber array were prepared in the same manner asin Example 1, except that polymer solution 7 was used instead of polymersolution 1.

[Polymer solution 7] Comb polymer (D)  5 parts by mass 1,4-dioxane 95parts by mass

Gel did not become detached from the inner walls at the time of slicing.Thus, it was confirmed that the adhesion at the interface between theinner walls of the hollow fibers and the gel was sufficiently strong.The conditions of the gel in the hollow portions were observed using astereoscopic microscope. As a result, all the 49 hollow fibers wereimpregnated with acrylamide gel without any spaces.

Comparative Example 1

Thin slices of a hollow fiber array were prepared in the same manner asin Example 1, except that polymer solution 8 was used instead of polymersolution 1.

[Polymer solution 8] Copolymer of methyl methacrylate  5 parts by massand methacrylic acid (Coating Resin PB 2322, manufactured by MitsubishiRayon Co., Ltd.) Ethanol 95 parts by mass

The conditions of the gel in the hollow portion were observed. As aresult, it was found that none of the gel had become detached from thehollow portion, although a gap was observed at the interface between theinner wall of the hollow fiber and the gel.

All publications, patents, and patent applications cited herein areincorporated herein by reference in their entirety.

INDUSTRIAL APPLICABILITY

Use of hollow fibers having comb polymers introduced on their innerwalls can provide hollow fibers impregnated with gel in which the gel isfirmly retained on the inner walls of hollow fibers. Thin slicesobtained by bundling these hollow fibers and slicing the bundle havesufficient adhesion between the gel and the inner walls of hollowfibers.

1. Hollow fibers impregnated with gel and having comb polymersintroduced on their inner walls, wherein the hollow portions of thehollow fibers are filled with gel, and wherein the hollow fibers arenon-porous.
 2. The hollow fibers impregnated with gel according to claim1, wherein the gel is mainly composed of an acrylamide monomer. 3.Hollow fibers impregnated with gel, wherein organism-associatedsubstances are retained in the gel in the hollow fibers impregnated withgel according to claim
 1. 4. A hollow fiber array, wherein several ofthe hollow fibers impregnated with gel according to claim 1 are bundled.5. The hollow fiber array according to claim 4, which comprises 100 ormore fibers per cm² thereon.
 6. Thin slices of the hollow fiber array,which are prepared by cross-sectioning the hollow fiber array accordingto claim
 4. 7. The hollow fiber array of claim 4, wherein the fibers arebundled lengthwise and the hollow fiber array has at least one facedefined by a single plane comprising a plurality of pores, each porecorresponding with a face of one of the hollow fibers.
 8. The hollowfibers according to claim 1, wherein the gel is immobilized on the innerwalls of the hollow fibers.
 9. The hollow fibers of claim 1, wherein thecomb polymers have polymerizable functional groups.
 10. The hollowfibers of claim 1, wherein the comb polymers have hydrophilic functionalgroups.
 11. The hollow fibers of claim 10, wherein the comb polymershave at their side chain a polymer selected from the group consisting ofpolyhydroxyethylmethacrylate, polyethyleneglycol, polyacrylamide, andmixtures thereof.
 12. A hollow fiber impregnated with gel and having oneor more comb polymers introduced on an inner wall, wherein the hollowportion of the hollow fiber is filled with gel, and wherein the hollowfiber is a non-porous capillary.
 13. The hollow fiber of claim 12,wherein the gel mainly comprises an acrylamide monomer.
 14. The hollowfiber of claim 12, wherein one or more organism-associated substances isretained in the gel in the hollow fibers.
 15. A hollow fiber array,comprising: a plurality of the hollow fibers of claim 12, wherein thefibers are bundled.
 16. The hollow fiber array of claim 15, whichcomprises 100 or more of the fibers per cm².
 17. A thin slice of ahollow fiber array, prepared by cross-sectioning the hollow fiber arrayof claim
 16. 18. The hollow fiber array of claim 15, wherein the fibersare bundled lengthwise and the hollow fiber array has at least one facedefined by a single plane comprising a plurality of pores, each porecorresponding with a face of one of the hollow fibers.
 19. The hollowfiber of claim 12, wherein the gel is immobilized on the inner wall ofthe hollow fiber.
 20. The hollow fiber of claim 12, wherein the combpolymer has one or more polymerizable functional groups.
 21. The hollowfiber of claim 12, wherein the comb polymer has one or more hydrophilicfunctional groups.
 22. The hollow fiber of claim 21, wherein the combpolymer has as a side chain at least one polymer selected from the groupconsisting of polyhydroxyethylmethacrylate, polyethyleneglycol andpolyacrylamide.